The present invention relates to perimeter truss structures for space borne antennas. In particular, the present invention relates to a deployable perimeter truss structure that folds into a compact volume for launch.
Industry has continued to improve space deployable reflector antennas for over 30 years. In the past, reflector antenna designs included a cantilever radial rib structure that supported an elastic shaped mesh. However, the radial rib structure required elaborate manufacturing, assembly, and alignment techniques, while the elastic mesh required a great deal of time, labor, and expense to attach. Because the rib structure had an inherently high weight, some past reflector antennas attempted to substitute a labyrinth of expensive caternaries including radial and cross cords to develop the density of control points required to shape the elastic mesh properly. A common difficulty associated with these past approaches, however, was that the resulting structures suffered from high weight and large stowed volume.
Space borne antennas, of course, reach orbit in a launch vehicle. Launch vehicles are extremely expensive, and any reduction in payload size and weight generally results in reduced launch cost. Past radial rib structures in particular, however, required very large volume inside a launch vehicle shroud. As a result, larger shrouds and larger launch vehicles were required.
The cost difference between launch vehicles can be enormous. As one example, a satellite launched by an ATLAS rocket incurs an approximately $185 million launch cost, while a satellite with an antenna that requires a larger TITAN launch vehicle incurs an approximately $400 million launch cost. Thus, although large antennas are generally desirable, the large stowed size and weight of such antennas, in the past, presented an enormous launch and manufacturing cost hurdle.
A need has long existed for a cost effective, lightweight, large aperture antenna support structure that folds into a compact volume for launch.